The discovery of a anew family with a genetic deficiency of the second component of complement (C2) requires development of methods to study human C2 biosynthesis in vitro without risk to the patient. Accordingly, methods for preparation and long term culture of human peripheral blood monocytes will be developed. The capacity of these normal cells to synthesize C2 will be compared to that of cells obtained from C2 deficient patients. Studies of complement biosynthesis by synovial tissues obtained from patients with rheumatoid arthritis will be compared to synthesis of complement by synovium ofpatients with traumatic and/or degenerative arthritis.